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1 .\" $NetBSD: gzip.1,v 1.20 2009/04/01 08:15:37 mrg Exp $
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3 .\" Copyright (c) 1997, 2003, 2004 Matthew R. Green
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27 .Dd July 28, 2009
28 .Dt GZIP 1
29 .Os
30 .Sh NAME
31 .Nm gzip
32 .Nd compression/decompression tool using Lempel-Ziv coding (LZ77)
33 .Sh SYNOPSIS
34 .Nm
35 .Op Fl cdfhklNnqrtVv
36 .Op Fl S Ar suffix
37 .Ar file
38 .Oo
39 .Ar file Oo ...
40 .Oc
41 .Oc
42 .Nm gunzip
43 .Op Fl cfhkNqrtVv
44 .Op Fl S Ar suffix
45 .Ar file
46 .Oo
47 .Ar file Oo ...
48 .Oc
49 .Oc
50 .Nm zcat
51 .Op Fl fhV
52 .Ar file
53 .Oo
54 .Ar file Oo ...
55 .Oc
56 .Oc
57 .Sh DESCRIPTION
58 The
59 .Nm
60 program compresses and decompresses files using Lempel-Ziv coding
61 (LZ77).
62 If no
63 .Ar files
64 are specified,
65 .Nm
66 will compress from standard input, or decompress to standard output.
67 When in compression mode, each
68 .Ar file
69 will be replaced with another file with the suffix, set by the
70 .Fl S Ar suffix
71 option, added, if possible.
72 In decompression mode, each
73 .Ar file
74 will be checked for existence, as will the file with the suffix
75 added.
76 .Pp
77 If invoked as
78 .Nm gunzip
79 then the
80 .Fl d
81 option is enabled.
82 If invoked as
83 .Nm zcat
84 or
85 .Nm gzcat
86 then both the
87 .Fl c
88 and
89 .Fl d
90 options are enabled.
91 .Pp
92 This version of
93 .Nm
94 is also capable of decompressing files compressed using
95 .Xr pack 1 ,
96 .Xr compress 1
97 or
98 .Xr bzip2 1 .
99 .Sh OPTIONS
100 The following options are available:
101 .Bl -tag -width XXrXXXrecursiveX
102 .It Fl 1 , -fast
103 .It Fl 2
104 .It Fl 3
105 .It Fl 4
106 .It Fl 5
107 .It Fl 6
108 .It Fl 7
109 .It Fl 8
110 .It Fl 9 , -best
111 These options change the compression level used, with the
112 .Fl 1
113 option being the fastest, with less compression, and the
114 .Fl 9
115 option being the slowest, with optimal compression.
116 The default compression level is 6.
117 .It Fl c , -stdout , -to-stdout
118 This option specifies that output will go to the standard output
119 stream, leaving files intact.
120 .It Fl d , -decompress , -uncompress
121 This option selects decompression rather than compression.
122 .It Fl f , -force
123 This option turns on force mode.
124 This allows files with multiple links, overwriting of pre-existing
125 files, reading from or writing to a terminal, and when combined
126 with the
127 .Fl c
128 option, allowing non-compressed data to pass through unchanged.
129 .It Fl h , -help
130 This option prints a usage summary and exits.
131 .It Fl k , -keep
132 Keep (don't delete) input files during compression
133 or decompression.
134 .It Fl l , -list
135 This option displays information about the file's compressed and
136 uncompressed size, ratio, uncompressed name.
137 With the
138 .Fl v
139 option, it also displays the compression method, CRC, date and time
140 embedded in the file.
141 .It Fl N , -name
142 This option causes the stored filename in the input file to be used
143 as the output file.
144 .It Fl n , -no-name
145 This option stops the filename and timestamp from being stored in
146 the output file.
147 .It Fl q , -quiet
148 With this option, no warnings or errors are printed.
149 .It Fl r , -recursive
150 This option is used to
151 .Nm
152 the files in a directory tree individually, using the
153 .Xr fts 3
154 library.
155 .It Fl S Ar suffix , Fl -suffix Ar suffix
156 This option changes the default suffix from .gz to
157 .Ar suffix .
158 .It Fl t , -test
159 This option will test compressed files for integrity.
160 .It Fl V , -version
161 This option prints the version of the
162 .Nm
163 program.
164 .It Fl v , -verbose
165 This option turns on verbose mode, which prints the compression
166 ratio for each file compressed.
167 .El
168 .Sh ENVIRONMENT
169 If the environment variable
170 .Ev GZIP
171 is set, it is parsed as a white-space separated list of options
172 handled before any options on the command line.
173 Options on the command line will override anything in
174 .Ev GZIP .
175 .Sh SEE ALSO
176 .Xr bzip2 1 ,
177 .Xr compress 1 ,
178 .Xr fts 3 ,
179 .Xr zlib 3
180 .Sh HISTORY
181 The
182 .Nm
183 program was originally written by Jean-loup Gailly, licensed under
184 the GNU Public Licence.
185 Matthew R. Green wrote a simple front end for
186 .Nx 1.3
187 distribution media, based on the freely re-distributable zlib library.
188 It was enhanced to be mostly feature-compatible with the original
189 GNU
190 .Nm
191 program for
192 .Nx 2.0 .
193 .Pp
194 This manual documents
195 .Nx
196 .Nm
197 version 20040427.
198 .Sh AUTHORS
199 This implementation of
200 .Nm
201 was written by
202 .An Matthew R. Green Aq Mt mrg@eterna.com.au .